Last week, Wendy Seltzer (Brooklyn Law) and Fritz Attaway (MPAA) debate DRM at the WSJ: 'DRM' Protects Downloads, But Does It Stifle Innovation?. The difference in opinions is about how end users relate to copyrightable works. The strong copyright/pro-DRM view is that once is a work is fixed, it is inviolably fixed in that particular arrangement unless the copyright owner decides to offer a different version. The argument against DRM is that copyright law allows individuals to use a particular copy of a work in any manner they want-- such as cutting up a book and stapling the pages together out of order-- but DRM makes it impossible to engage in these uses that are permissible under copyright.
The copyright maximalists are concerned about indiscriminate redistribution. The anti-copyright advocates are concerned with restrictions on lawful use. It is difficult to distinguish between the uses necessary for each end result, so to prevent indiscriminate redistribution constricts the ability to use lawfully acquired material. But the digital formats that allow users to remix and repurpose lawfully acquired copies in non-infringing manners also allow for indiscriminate redistribution.
A technological system can restrict the ability to make copies. The law can be fuzzier, because the boundaries between infringement, fair use, and non-infringing use are not clearly delineated-- context is crucial.